It sounds like retarded timing to me. I dont know how it could have possibly got this way, but I'd check it just to make sure. Timing lights aren't that expensive.

I'm not exactly sure if those had vacuum advance, but if it does, unplug it at idle from the distributor, plug it with a golf tee or something, and set the timing at 10 degrees BTDC. Plug the vacuum advance hose back in and try it. I have a feeling this may solve some of your problems.